The present invention generally relates to a door closing apparatus and more particularly to a closer apparatus for automatically returning a sliding door to a closed position at a controlled rate.
Sliding doors are commonly used in both residential and commercial installations. Generally these doors are constructed having a rectangular frame which retains one or more glass panels. A common sliding door of this type is termed an xe2x80x9cArcadiaxe2x80x9d door and has a fixed section adjacent the sliding section which fixed section generally including a large glass panel. The sliding panel is supported along the lower edge of the door on rollers movable in a track. This type door may also have hangers with rollers which move in a track along the upper horizontal edge of the door. Doors of this type are quite heavy, particularly those having steel frames, and, as such, require considerable manual effort to open and close the doors. Accordingly, it is not uncommon for individuals, particularly children, to open the door when entering or exiting and leave the door in the open position. This results in a considerable waste of energy as during summer cool air is allowed to escape through the opening and during winter months heated air within the structure will escape.
Additional inconveniences, as a result of a door left open, includes entry of insects, dirt and dust. Another problem that results from doors of this type being inadvertently left open is that the opening may present a safety hazard, as a small toddler or child may crawl or walk through the opening and wander away and encounter hazards such as backward swimming pools or street traffic.
As a result, efforts have been made to provide closing mechanisms for sliding doors of this general type. One such approach, which has achieved considerable success, is the present inventor""s apparatus for closing sliding doors as disclosed in U.S. Pat. No. 5,365,636 and sold under the trademark The Klozit. Briefly described, The Klozit device, is an apparatus for returning a sliding door from an open position to a closed position which includes a compressible spring mechanism. The compressible spring mechanism exerts a biasing force tending to extend the rod of the spring mechanism. A cable is secured at a first end to the sliding door and is secured its opposing end to the fixed door frame. The first end of the cable is secured in a fixed position relative one of the two ends of the spring mechanism. The cable extends about a first and second pulley. As the door is opened, tension is applied to the cable and the first and second pulleys exert a compressive force to shorten the length of the compressible spring mechanism. When the door is released, the compressible spring mechanism returns to its extended length causing the door to return towards its closed position. The Klozit device has achieved commercial success and is effective for its intended purpose and it represents a substantial improvement over prior art devices. However, the Klozit device utilizes a series of pulleys which inherently impose frictional resistance. Further, use of multiple pulleys increases the mechanical complexity of the device.
Accordingly, the present invention provides an improved door closing apparatus (termed a xe2x80x9ccloserxe2x80x9d) for automatically closing a sliding door which closer device is efficient, compact, unobtrusive, and operates with reduced frictional forces so that the manual opening force required is reduced while still providing adequate closing force.
It is a primary object of the present invention to provide a sliding door closing system which automatically closes a sliding door at a safe, controlled speed.
It is yet another object of the present invention to provide a sliding door closing apparatus which is inexpensive to manufacture and can easily be installed both on new and existing doors.
It is an object of the present invention to provide a closer for sliding doors which is xe2x80x9carmedxe2x80x9d as the user applies a manual opening force and which operates with minimal frictional loss.
It still another object of the present invention to provide automatic sliding door closing system which cushions the door as the door closes approaching the door jamb, thus reducing the possibility of injury to persons, as well as to pets.
Briefly, the present invention relates to a closer apparatus for returning a sliding door to a closed position. A compressible spring has a rod with an extended and retracted position. A cable reel is rotatably supported in a housing and has an attached cable which extends around a pulley on the end of the rod. The opposite end of the cable is fixed. As the door is opened, the cable reel is rotated and tension is applied to the cable which will force the rod toward its retracted position. When the door is released, the compressible spring will return the rod to its extended length.
A spool is rotatable with the reel and mounted on a common shaft. The spool and reel are wound in opposite directions. The spool has a core having a radius which is greater than the radius of the core of the reel so a mechanical advantage is achieved. The line on the spool preferably is a strong flat tape. The spool and reel assembly, spring and pulley are within the housing which housing is securable to a door frame member. The free end of the spool line is affixed to the door frame preferably along the upper horizontal section.
The compressible spring member may be a simple coil spring or a cylinder with a piston and rod and having a compressible coil spring in the head end chamber. However, it is preferred the compressible spring be a gas spring of the type containing a pressurized gas which urges or biases a piston and attached rod to the extended position or a positioning apparatus including a set of magnets that exert a magnetic force to urge a rod or shaft in one direction.
When a manual opening force is applied to the door, the rod of the compressible spring will be retracted as the spool will rotate in a direction to pay out line and rotation will cause the cable on the reel to be wound onto the reel. When the opening force is released, the compressible spring will urge the rod and pulley on the end of the rod to an extended position rotating the reel in the opposite direction and simultaneously causing the line attached to the spool to rewind exerting a closing force. As the door approaches the jamb, the compressible spring has a dampening feature to slow the return of the door.
The apparatus can be retrofit to existing doors or incorporated in a door assembly as an item of original manufacture.